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Police forces across the UK successfully lobbied to use a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces use the national police database to conduct retrospective facial recognition searches. This process involves matching a reference photograph of a person of interest against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered NPL review concluded the system was more likely to suggest incorrect matches for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was producing a lower number of “investigative leads”. Internal records indicate the stricter setting reduced the number of searches resulting in potential matches from over half to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review found the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The ministry stated on these results: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the police records state: “The change greatly lessens the effect of bias across protected characteristics of race, generation and sex but had a significant negative impact on operational effectiveness”. The papers further note that forces complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to expand the use of facial recognition technology. The minister for police the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was very little discussion in race action plan meetings of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made via the race action plan are not being translated into wider practice. Our reports have cautioned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson stated: “The Home Office takes the findings of the report seriously and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers carefully reviewing the output.”